Currently, metamaterials can be formed with repeating and periodic structures. Metamaterials can be materially engineered to have desired properties (e.g., a desired index of refraction). Metamaterials can have properties that depend on physical placement of the elements in the metamaterial. There are currently many types of metamaterials, including electric metamaterials and magnetic materials.
Current metamaterials can have a negative index of refraction at its resonant frequency. These current metamaterials can be limiting in that in order for incident electromagnetic waves to propagate in the metamaterial, the incident electromagnetic wave typically has to impinge upon the metamaterial with a particular polarization. For example, an electric field component and a magnetic field component of the incident electromagnetic wave may be required to align with certain components in the metamaterial in a particular direction in order for the incident wave to propagate through the metamaterial with a negative index of refraction.
Therefore, it can be desirable to have a metamaterial with a negative index of refraction that can propagate an incident electromagnetic wave having any polarization direction.